Mitral Regurgitation

What is Mitral Regurgitation?

Mitral regurgitation, or MR, is the most common type of heart valve problem affecting more than 2% of all people; this often increases as you get older. This issue happens when blood flows backwards from the left ventricle (main pumping chamber of the heart) to the left atrium (the chamber that receives blood before being pumped to the rest of the body), through the mitral valve. This creates a sound that can be heard through a stethoscope at the lower left side of your chest.

Let’s look at the structure of the Mitral Valve:

Your mitral valve is composed of two small flaps, one at the front (anterior) and one at the back (posterior) set within a surrounding structure known as an annulus. The flap at the back (posterior) comes from the inner lining of the heart’s left atrium. Support for these flaps comes from two small muscle groups attached to the heart wall (papillary muscles) and a set of tendons (chordae tendineae).

There are two main types of Mitral Regurgitation:

1. Primary Mitral Regurgitation: This is sometimes called degenerative or organic. It happens when there is physical damage or changes to the flaps, tendons, or muscles which help the valve to close correctly during each heartbeat. Common causes are rupture of the muscles, mitral valve prolapse (when flaps bulge backwards), or a tear in the flaps.

2. Secondary Mitral Regurgitation: Also known as functional or ischemic. This is not due to a problem with the valve itself, but rather due to abnormal movements of the heart wall or changes to the heart structure. This results in enlargement or moving of the muscles, causing the blood to flow backwards through flaps that don’t close properly.

There is also a classification system known as the Carpentier Classification, which categorizes mitral regurgitation into three types based on the movement of the valve flaps:

1. Type 1: Normal flap movement. Can be caused by widening of the annulus or a tear in the flaps with the backflow of blood being directed centrally.

2. Type 2: Too much flap movement. This can be due to rupture of the muscles or tendons, or excess tendons, with the backflow of blood being directed away from the involved flap.

3. Type 3: Restricted flap movement, which can be either throughout the full heartbeat cycle (Type IIIa, often caused by a common inflammation of the heart disease), or just when the heart is contracting (Type IIIb, often caused by muscle dysfunction or dilation of the left ventricle). Both scenarios have a mixture of central or eccentrically directed blood flow.

What Causes Mitral Regurgitation?

Mitral regurgitation is a condition where the mitral valve in your heart does not close properly which allows blood to flow backward in your heart. The condition can happen due to several reasons. Let’s look at some of them.

One reason is the wearing out or degeneration of the valve due to age or conditions that affect body tissues, like Marfan syndrome, Ehlers-Danlos syndrome, and systemic lupus erythematosus. These conditions can cause the valve to droop or prolapse, leading to leakage.

Some people are born with conditions that cause the problem. These include an isolated cleft of the mitral valve, a double orifice mitral valve, and a parachute mitral valve where the strings that control the valve are attached to a single muscle. These are all rare, but well-known causes of mitral regurgitation.

In developing countries, rheumatic heart disease, an illness that affects heart valves, is common because of limited medical resources and immunization programs. This disease is usually caused by strep throat and can significantly damage the mitral valve.

When the left ventricle, the main pumping chamber of the heart, enlarges due to conditions like cardiomyopathy (heart muscle diseases), it can disrupt the closing of the mitral valve, leading to leakages. In other cases, the muscles that control the valve can burst, usually after a heart attack or subsequent infection-causing serious leakage.

Sometimes, a previous heart attack can damage the area around the mitral valve, causing it to leak. The severity of this leakage can increase or decrease with exercise, depending on changes in the heart muscle and valve shape.

In people suffering from heart failure, where the heart cannot pump enough blood to meet the body’s needs, mitral regurgitation is quite common. It is usually determined by the severity of the heart failure.

Atrial fibrillation, a condition characterized by irregular heart rhythm, can also cause mitral regurgitation. Regulating the irregular heart rhythm can help reduce the leakage.

Lastly, a condition called hypertrophic cardiomyopathy, characterized by the thickening of the heart muscle, can lead to the enlargement of the muscles controlling the mitral valve, causing it to leak.

Understanding the underlying causes of mitral regurgitation can be beneficial in its management and treatment.

Risk Factors and Frequency for Mitral Regurgitation

Mitral regurgitation is a typical heart valve issue that affects about 10% of people. The most common cause of this condition is mitral valve prolapse, which is linked to a specific kind of deterioration in the mitral valve. This problem is the most common heart valve disease worldwide and affects about 2% to 3% of people. In places where many people are still developing, like some countries, rheumatic heart disease is very common and often leads to hospital admissions because of complications with the mitral valve.

Signs and Symptoms of Mitral Regurgitation

Mitral valve regurgitation is characterized by a specific sound or “murmur” that can best be heard when examining the apex of the heart. This murmur can spread or radiate toward the left underarm area. It’s important to distinguish this sound from other heart-related murmurs. Some common situations where different heart murmurs might be present include:

• Mitral valve prolapse in which an early systolic murmur is heard best near the heart’s apex, but there’s a middle-systolic click.
• Tricuspid regurgitation wherethe murmur is high-pitched, blowing, and holosystolic, best heard near the lower left sternal border, and can spread to the right lower sternal border; it becomes louder with deep in-breath.
• Ventral septal defect features a holosystolic murmur with the louder defect leading to a quieter murmur.
• Aortic stenosis where there’s a mid-systolic, crescendo-decrescendo murmur that radiates toward the neck; it becomes quieter with Valsalva maneuver or standing.

Other heart conditions can also produce similar murmurs. Pulmonic stenosis gives a mid-systolic, crescendo-decrescendo murmur that increases in intensity during inspiration.

If we move on to the symptoms and signs of mitral regurgitation, they can be split into two groups. Some symptoms are directly caused by the heart condition itself, while others are associated with the underlying cause. It’s crucial to consider all possible explanations and not to tunnel in on a single one.

For example, acute mitral regurgitation can start suddenly, and patients may experience symptoms such as severe breathlessness even at rest, coughing up clear or pink frothy mucus. There is also discomfort or pain in the chest that spreads to the neck, jaw, shoulders, or upper arms, often accompanied by nausea and profuse sweating. Patients may also present with altered consciousness, rapid heart rate or slow heart rate if the heart’s electrical system is affected by ischemia, low blood pressure, rapid breathing, low oxygen levels, and bluish skin tone. Additionally, in severe cases, there could be swelling of neck veins, crackling sounds in the lungs, and a particular type of heart murmur that can be felt at the apex of the heart and radiates to the armpit.

Generally, acute MR result from a tear in the muscular structure located in the ventricles of the heart, which can occur due to severe coronary artery disease, or from rapid destruction of the heart valve due to a severe bacterial infection.

On the other hand, patients with chronic mitral regurgitation often have no symptoms until the disease has progressed to a severe stage. Common symptoms include tiredness, shortness of breath during physical exertion, difficulty breathing when lying flat, sudden episodes of shortness of breath at night, swelling in the legs, weight gain, swelling of the neck veins, widening of the pulse pressure, a displaced pulsating sensation in the chest and a specific type of heart murmur that can be felt at the apex of the heart and radiates to the armpit. In severe cases, there may also be fainting or near fainting, bluish skin tone, unusual curving of the fingers (clubbing), enlarged liver, signs of fluid in the abdomen, overall swelling of the body, and sign of fluid in the pleural space or pericardium. These are indications of an increase in blood pressure in the lungs and resultant dysfunction of the right ventricle of the heart due to chronic pressure overload. The number of potential causes for these symptoms is quite wide, with different clinical signs depending on the underlying cause.

Testing for Mitral Regurgitation

For assessing the heart condition known as mitral regurgitation, your doctor’s assessment and attention to your symptoms are the main guides for ordering appropriate tests.

Echocardiogram

An echocardiogram is often the main test used to diagnose and evaluate mitral regurgitation, a condition where your heart’s mitral valve doesn’t close tightly. This test can provide a detailed image of your heart and help track the blood flowing through your heart and valves.

There are ways to measure the severity of mitral regurgitation, such as vena contracta, a technique that measures the width of the abnormal backwards blood flow seen in this condition. Another method, the Doppler volumetric method, measures the amount of backward flow subtracted from the forward flow in the heart.

After an initial echocardiogram, follow-up studies are suggested for patients with moderate to severe mitral regurgitation every few months to years, depending on severity.

Once the mitral valve has been repaired, successful treatment can be confirmed by examining the height of the valve’s leaflets from the base of the valve at the height of the heartbeat, as well as other measurements of valve positioning.

Electrocardiogram 

An EKG (electrocardiogram) can also help evaluate mitral regurgitation, specifically identifying abnormal heart rhythms like atrial fibrillation, which is common in patients with this condition.

Chest X-Ray

A chest x-ray may show enlarged parts of the heart, a result of persistent mitral regurgitation.

Exercise Stress Testing

If you’re not experiencing symptoms but the mitral regurgitation is severe, an exercise stress test might help your doctor understand your exercise tolerance and whether your symptoms come out with increased heart demand.

Cardiac Catheterization

A more invasive test, cardiac catheterization can accurately measure the amount of backwards blood flow when other test results don’t match with clinical findings.

Cardiac MRI (Magnetic Resonance Imaging)

A cardiac MRI can also be a useful tool for measuring the severity of mitral regurgitation. While widely available, it should be considered when other imaging techniques can’t adequately explain the severity of your condition.

Biomarkers

A specific blood test, assessing the level of a protein called B-type natriuretic peptide (BNP), may give insights into the severity of symptoms and overall prognosis for individuals with mitral regurgitation. An elevated level of BNP, which is released by the heart in response to extra workload, may be associated with heart failure symptoms, heart function, or death in patients without symptoms but significant mitral regurgitation.

Treatment Options for Mitral Regurgitation

The choice between medical and surgical management of a condition called mitral regurgitation (MR), where a heart valve doesn’t close properly causing blood to leak backwards, depends on the severity, duration, associated health conditions, and cause of the MR. Certain medications may be used to treat MR, but the scientific evidence to support their use is not strong and neither the American College of Cardiology (ACC) nor the American Heart Association (AHA) definitively recommend them. Typically, severe MR is treated with a surgical procedure to fix or replace the faulty valve.

There are several types of drugs used for managing MR. Some medicines known as ACE inhibitors and ARBs have been used to delay the progress of MR in patients without symptoms. These drugs may reduce the amount of blood leaking backwards (regurgitant volume) and decrease the size of the left ventricle (LV, the heart’s main pumping chamber), but the studies do not entirely support their use. In fact, some studies have found that these drugs don’t improve survival and could make some patients worse.

Another group of drugs, beta-blockers, have also been studied for the treatment of MR. However, these results have shown little benefit in patients with primary MR, although some studies indicated that they may improve survival in secondary MR. Presently, the ACC/AHA does not provide specific recommendations regarding the use of beta-blockers for patients with MR.

Loop diuretics, another type of medication, are thought to be helpful in reducing afterload (pressure that the heart must work against to eject blood) and the amount of blood leaking backwards, but more studies are required to confirm this.

The decision to proceed with surgery for MR depends on the underlying cause. In cases where the valve is damaged due to cord or muscle rupture, or infective endocarditis (an infection of the inner lining of the heart), surgery is required. Patients with acute, symptomatic MR or those with a large leak area, as well as those with deteriorated heart function or a large left ventricle, need surgical intervention. Surgery is also indicated for patients with severe MR who either have symptoms or are asymptomatic but have a moderately reduced ejection fraction, a measure of how well the heart is pumping.

Heart valve repair surgery aims to attain a good surface area of contact between the mitral valve leaflets and to correct dilation of the valve. Generally, the ACC and the AHA recommend valve repair over valve replacement since it results in less recurrence of MR. The data also show lesser complications and death rate after repair as compared to replacement. However, in cases where there is significant tissue damage, as seen in some cases of infective endocarditis, valve replacement is preferred over repair.

When it comes to replacing the mitral valve, mechanical valves are usually preferred over bioprosthetic (tissue) valves due to their increased durability. Both types require anticoagulation – blood thinning medication – after surgery, but it’s temporary for bioprosthetic valves and lifelong for mechanical valves.

Mitraclip is another surgical procedure that has been proven effective and is associated with low complication and death rates. It’s especially useful in patients considered at high risk for traditional repair or replacement. However, it can reduce the mitral valve area, potentially leading to an issue called stenosis (narrowing), therefore it is not recommended for patients with a small mitral valve area.

What else can Mitral Regurgitation be?

When it comes to medical conditions related to Mitral Regurgitation (MR), doctors generally categorize the symptoms into two groups: symptoms directly related to MR itself, and those tied to the underlying cause. Recognizing a wide range of potential causes is key in order to accurately diagnose the condition. To start, doctors usually take a detailed medical history and conduct a physical examination, which helps determine whether the MR is an acute (sudden onset) or chronic (long-term) condition. This information can significantly help in narrowing down the possible causes, which could include:

• Worsening of congestive heart failure
• Acute coronary syndrome (a sudden reduction of blood flow to the heart muscle)
• Unstable heartbeat rhythm or dysrhythmia that affects blood flow
• Cardiac tamponade, fluid accumulation that impedes the heart’s normal function
• Pneumothorax, or collapsed lung
• Pulmonary embolism, a dangerous blood clot in the lungs
• Septic shock, a serious infection that affects the whole body
• Thyrotoxicosis or thyroid storm, a life-threatening case of overactive thyroid

The range of potential causes for chronic mitral regurgitation is also extensive, and specific symptoms often depend on the root cause of the condition.

What to expect with Mitral Regurgitation

Mitral regurgitation is a common condition that if not treated, can cause serious health problems, which makes it essential to find new ways to manage or treat it. Certain surgeries to repair or replace the mitral valve have been thoroughly studied and have been found to significantly improve symptoms and lower the risk of death.

Here are some important research findings:

* In one study of 144 people with mitral regurgitation, it was found that the 5-year death rate was 30%, compared to 13% in a similar group of people without the condition. This study also showed that people with functional mitral regurgitation, which means the valve isn’t working properly, had a higher increase in illness and death rates than those with structural problems.
* Another study looked at people aged 50 and older with mitral regurgitation who were treated with medications alone. The study showed that the yearly death rate for moderate and severe organic mitral regurgitation was 3% and 6%, respectively.

In another study of 83 patients (average age 56, and with no symptoms) who underwent earl mitral valve surgery, 1% needed re-repair for residual mitral regurgitation and 4% needed a permanent pacemaker. After surgery, the 10-year survival rate was 91.5%.

People with degenerative or rheumatic heart disease and an average age of 57 years who underwent mitral valve repair had comparable survival rates with the general population. In a study of 125 mitral valve repairs, 2.4% of the patients died soon after surgery and the 10-year survival rate was 84.3%.

One systematic review and meta-analysis looked at people with severe mitral regurgitation and a reduced heart pumping rate (ejection fraction under 40%). This study compared mitral valve repair surgery and mitral valve replacement surgery in terms of operation-related death. It was found that the death rate during or after mitral valve repair surgery was 5%, while it was 10% for mitral valve replacement.

Research also showed that the best predictor of a good prognosis and improvement of symptoms after mitral valve (MV) surgery was a pre-operation heart pumping rate of above 60%. Overall, mitral valve repair is associated with better survival rates and less illness or death compared to mitral valve replacement.

Possible Complications When Diagnosed with Mitral Regurgitation

Mitral regurgitation, or a leaky heart valve, can lead to complications such as:

• Heart failure, which can cause shortness of breath
• Rapid, irregular heartbeat (atrial fibrillation)
• Stroke caused by irregular heart rhythms
• High blood pressure in the lungs (pulmonary artery hypertension)
• Heart enlargement and cardiomegaly (abnormal enlargement of the heart)

On the other hand, surgery or replacement of the mitral valve may also lead to complications like:

• Infections, including heart valve infection (infective endocarditis)
• Bleeding
• Clotting and narrowing (stenosis) of the new valve
• Problems with the new valve functioning properly
• Rapid, irregular heartbeats (arrhythmias)
• Stroke
• Death

Recovery from Mitral Regurgitation

If a patient does not have any complications like infection or bleeding during or after the surgery, they are usually able to leave the hospital.

After surgery, there are a few guidelines to be followed:

* As soon as the surgery is completed, an ECG (or Electrocardiogram, which is a simple test that checks your heart’s rhythm and electrical activity) should be done before the patient is discharged. Regular ECGs are necessary to examine how the left side of the heart is functioning, especially if the patient begins to experience symptoms.
* Patients with mechanical or prosthetic heart valves need to take blood thinners, typically warfarin, for the rest of their lives.
* Doctors should give patients who have a mechanical or prosthetic heart valve or a history of endocarditis (an infection of the heart’s inner lining) antibiotics before they undergo dental, oral, or upper respiratory tract procedures. This is to prevent another infection of the heart.

After the surgery, doctors recommend exercise therapy and cardiac rehabilitation. These have been studied intensely and are known to improve the ability to exercise and the percentage of blood that is pumped out of the heart. But more research is needed to fully understand the benefits.

In a study of 105 patients who had heart valve surgery, the average time before they could return to work was about 5 months. The surgery also improved the amount of blood that gets pumped out of the heart. Comparing the results after surgery, it was seen that 78.4% were categorized in the first two stages of the New York Heart Association (NYHA) classification, which means they had little to no symptoms. Before surgery, only 38.1% of these patients were in the first two stages.

Preventing Mitral Regurgitation

Patients should be aware of the severe symptoms of Mitral Regurgitation (MR), which is a condition where the heart’s mitral valve doesn’t close tightly, and know when to get medical help. It’s also useful for patients with MR to be aware of when surgery might be needed and what treatment options are available. While surgery can help improve conditions and life quality for patients diagnosed with moderate or severe MR, it has not been shown to increase lifespan. This is why it’s not commonly recommended or performed.

In the case of older people (60 years and above), research has shown that surgeons often decide not to perform this surgery, as it doesn’t extend the patient’s life. Different factors influence this decision. A study of 1,741 people with MR showed that only about 60% received surgical treatment. This percentage decreased to about 55% in those over 60 years old. In another study involving 396 patients with severe MR, almost half were not operated on due to having other health conditions. When deciding whether to perform surgery, factors like heart performance, the patient’s age, and other health conditions are considered.

Patients with MR should talk to a heart specialist, or cardiologist, about managing their condition, since treatment options can vary based on several factors.